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prepare for local version of Gomory cuts

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2023-10-29 19:45:14 -07:00
parent 160971df60
commit 938a89e197
3 changed files with 39 additions and 1 deletions
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34
src/math/lp/int_solver.cpp
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@ -194,7 +194,11 @@ namespace lp {
if (r == lia_move::undef && m_patcher.should_apply()) r = m_patcher();
if (r == lia_move::undef && should_find_cube()) r = int_cube(*this)();
if (r == lia_move::undef && should_hnf_cut()) r = hnf_cut();
#if 1
if (r == lia_move::undef && should_gomory_cut()) r = gomory(*this)();
#else
if (r == lia_move::undef && should_gomory_cut()) r = local_gomory();
#endif
if (r == lia_move::undef) r = int_branch(*this)();
return r;
}
@ -914,5 +918,35 @@ namespace lp {
#endif
}
lia_move int_solver::local_gomory() {
for (unsigned i = 0; i < 4; ++i) {
m_ex->clear();
m_t.clear();
m_k.reset();
auto r = gomory(*this)();
IF_VERBOSE(3, verbose_stream() << i << " " << r << "\n");
if (r != lia_move::cut)
return r;
u_dependency* dep = nullptr;
for (auto c : *m_ex)
dep = lra.join_deps(lra.dep_manager().mk_leaf(c.ci()), dep);
lp::lpvar term_index = lra.add_term(get_term().coeffs_as_vector(), UINT_MAX);
term_index = lra.map_term_index_to_column_index(term_index);
lra.update_column_type_and_bound(term_index, is_upper() ? lp::lconstraint_kind::LE : lp::lconstraint_kind::GE, get_offset(), dep);
lra.find_feasible_solution();
if (!lra.is_feasible()) {
lra.get_infeasibility_explanation(*m_ex);
return lia_move::conflict;
}
}
m_ex->clear();
m_t.clear();
m_k.reset();
return lia_move::undef;
}
}